Insulated shipping container systems are used to transport a variety of temperature sensitive products and goods including, for example, biological products, perishable foodstuffs, and raw materials. The thermal objective for a container system is to maintain a predetermined temperature range to protect the payload, i.e., the product being shipped from experiencing harmful external environmental temperature fluctuations, where the two most basic components are refrigerant and thermal insulation. Typical insulated shipping container systems attempt to maintain a predetermined temperature, whether cooled or heated, and attempt to insulate the payload, i.e. the product being shipped, from experiencing external environmental temperature fluctuations.
Biological products such as blood, biopharmaceuticals, reagents and vaccines with registered storage refrigeration conditions are commonly transported using insulated shipping containers. Because of these products' susceptibility to the external environmental temperature, increased regulatory scrutiny of product transport conditions have been implemented to ensure the viability of the product being shipped. Accordingly, shippers have had to make costly upgrades to their container systems to ensure compliance.
Current insulated shipping container systems use insulating material to protect the payload from external environmental temperatures. In addition, the insulating material protects the internal temperature from external temperature fluctuations. Typical insulating materials include expanded polystyrene and/or rigid polyurethane.
Current industry consensus is that high performance thermal insulation will remedy compliance requirements. This is in no way an assurance nor is it pragmatic. In order to combat increasing regulatory scrutiny and keep cost at a minimum and maximize functionality, future container systems must perform more efficiently using conventional materials. Thermal insulation is essential in protecting payloads from their thermal environment, but they do very little in keeping payloads cool. Instead, refrigerants and their use must be improved to achieve maximum efficiency.
Payloads are typically cooled using refrigerants that reside in the interior cavity formed by the insulating material. Refrigerants most typically used include ice, dry ice, gel packs, foam refrigerant, and the like. In conventional container systems cooling between refrigerant and payload is achieved by direct contact between refrigerants and payload. Chilled refrigerant is placed between subzero (° C.) frozen refrigerant and payload. The frozen and chilled refrigerant now forms a refrigerant system. The payload temperature is regulated by adjusting the amount and surface-to-surface contact of the chilled refrigerant onto the payload in conjunction with adjusting the amount and surface-to-surface contact of the frozen refrigerant onto the chilled refrigerant. The most functional configuration for shippers using this method is to locate the refrigerant system above the payload in contact with a single payload surface. This particular configuration is most effective in distributing small payloads and has limited cooling capacity and lack uniform cooling due to the limited contact between the refrigerant system and payload. This configuration must be abandoned when considering larger payloads and/or greater cooling. In order for this method to accommodate large payloads and/or greater cooling the refrigerant system must be expanded across additional payload surfaces, subsequently adding considerable weight to the container system and reducing functionality. Added weight and burden translates to increased cost. Ineffective refrigerant migration is another fault with this method, increasing the risk of failure. In addition, current insulated shipping containers have seams that are susceptible to air leaks, thereby negatively impacting the insulating properties of the insulating materials and reducing the efficiency of the refrigerant.
Recent attempts to improve typical insulated shipping containers have met with mixed success. In one example, an insulated shipping container is provided whereby the refrigerant is placed on a tray, separate from the payload. See, e.g. U.S. Pat. No. 4,576,017 to Combs et al., incorporated herein by reference. While this design attempts to minimizes the problems associated with putting the refrigerant in direct contact with the payload, the efficiency of the refrigerant is reduced requiring the use of more refrigerant to achieve a desired cooling effect, adding to the overall cost of these types of insulation shipping containers. In addition, the insulating properties of the refrigerant supporting tray further reduce the cooling properties of the refrigerant, requiring the use of more refrigerant and lower minimum refrigerant operating temperatures to achieve the desired cooling temperature, which in turn may lead to damage to the payload. Similarly, the '017 patent discloses attempts to increase the convective cooling that takes place inside the cavity of the shipping container by creating grooves, channels, or protrusions to increase the air flow around the payload. The designs of this and other systems, however, continue to have deleterious effects, especially with respect to the base or bottom of the payload, as there is sufficient contact between the payload and protrusions in these systems which in turn reduce air flow around critical parts of the payload, leading to uneven cooling of the payload. Furthermore these designs continue to be costly, difficult to construct, not scalable, and not capable of being a part of a prepackaging or automated packaging system.
In order to combat increasing regulatory scrutiny and keep cost at a minimum and maximize functionality, future container systems must perform more efficiently using conventional materials. Accordingly, there is a need for improved shipping containers and systems to provide cost effective, scalable, and workable solutions demanded by the extreme requirements of shipping temperature sensitive goods and products.